A method for selecting detection area of ​​synthetic aperture radar

Abstract

The present invention discloses a method for selecting a synthetic aperture radar (SAR) detection area. This method, pertaining to the field of SAR detection technology, addresses the prior art issue of random SAR detection and image acquisition, resulting in the possibility that the captured images may not meet requirements. The method comprises: a SAR radar controller sending a detection area prediction instruction; calculating a ground reflection coefficient matrix, a range resolution matrix, and an azimuth resolution matrix for grid points at different range resolutions; screening the range resolution, azimuth resolution, and ground reflection coefficient according to a threshold range to obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient requirements, graphically displaying them, obtaining a two-dimensional analysis graph, and generating a parameter table; and a SAR radar controller receiving the parameter table and performing image detection. This method can be used for selecting a SAR detection area.

Description

Technical Field

[0001] The present invention belongs to the field of synthetic aperture radar detection technology, and in particular relates to a method for selecting a synthetic aperture radar detection area. Background Art

[0002] Synthetic aperture radar is an active earth observation system that can be installed on flying platforms such as aircraft, satellites, and spacecraft to conduct earth observations around the clock and in all weather conditions, and has a certain surface penetration capability.

[0003] In the prior art, when a synthetic aperture radar needs to perform detection, detection and image acquisition are usually performed directly.

[0004] However, the detection and image acquisition by synthetic aperture radar in the above manner is random, and the images acquired may not meet the requirements. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a method for selecting a synthetic aperture radar detection area, which solves the problem in the prior art that synthetic aperture radar detection and image acquisition are random, resulting in the collected image may not meet the requirements.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions:

[0007] The present invention provides a method for selecting a synthetic aperture radar detection area, comprising the following steps:

[0008] The synthetic aperture radar is turned on, and the radar controller of the synthetic aperture radar sends a detection area prediction instruction;

[0009] According to the prediction instructions of the detection area, the ground reflection coefficient matrix, the distance resolution matrix and the azimuth resolution matrix of the grid points at different distance resolutions are calculated respectively;

[0010] According to the threshold range of the range resolution, the threshold range of the azimuth resolution and the threshold range of the ground reflection coefficient, the range resolution in the range resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix and the ground reflection coefficient in the ground reflection coefficient matrix are screened respectively, and a plurality of grid points meeting the conditions of the range resolution, azimuth resolution and ground reflection coefficient are obtained and graphically displayed to obtain a two-dimensional analysis diagram, and a parameter table of the range resolution, azimuth resolution, ground reflection coefficient, coordinates, flight parameters of the carrier, off-axis angle and antenna installation angle corresponding to the plurality of grid points meeting the conditions is generated;

[0011] The radar controller of the synthetic aperture radar receives the parameter table and performs image detection of the detection area that meets the range resolution, azimuth resolution and ground reflection coefficient according to the parameters in the parameter table.

[0012] Furthermore, the radar equation is calculated based on the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the system loss and the average power of the radar to obtain the ground reflection coefficient matrix of the grid point at different distance resolutions.

[0013] Furthermore, system loss includes waveform loss and transmission loss.

[0014] Furthermore, the ground reflection coefficient matrix of the grid points at different resolutions uses the following formula:

[0015]

[0016] Where σ is the ground reflection coefficient matrix, R is the slant range matrix, K = 1.38 × 10 -23 is the Boltzmann constant, T0 is the noise temperature, F n is the noise coefficient, L is the system loss, v is the sum velocity of the carrier in the north-east plane in the navigation coordinate system, θ is the oblique viewing angle matrix, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution, and k=1.4 is the azimuth broadening factor.

[0017] Furthermore, the range resolution matrix of the grid points is obtained according to the bandwidth of the radar, the height of the carrier and the slant range matrix.

[0018] Furthermore, the distance resolution matrix D r Use the following formula:

[0019]

[0020]

[0021] Among them, D r is the distance resolution matrix, R is the slant range matrix, B r is the bandwidth of the radar, (P x ,P y ,P z ) is the coordinate of the carrier in the navigation coordinate system, k is the azimuth broadening factor, c is the speed of light, and β is the ground-grabbing angle.

[0022] Furthermore, the azimuth resolution matrix of the grid points is obtained according to the carrier's velocity, wavelength, synthetic aperture time, slant angle matrix and slant range matrix.

[0023] Furthermore, the azimuth resolution matrix D a Use the following formula:

[0024]

[0025] Among them, D a is the azimuth resolution matrix, k is the azimuth broadening factor, λ is the wavelength, R is the slant range matrix, v is the sum velocity of the carrier in the northeast plane in the navigation coordinate system, θ is the slant angle matrix, T a is the synthetic aperture time.

[0026] Furthermore, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0027] Step a: Determine whether the range resolution in the range resolution matrix is ​​within the range resolution threshold range. If so, determine whether the grid point corresponding to the range resolution meets the conditions, and obtain multiple grid points that meet the range resolution.

[0028] Step b: determining whether the azimuth resolution of the plurality of grid points satisfying the range resolution is within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the condition, and obtaining a plurality of grid points satisfying both the range resolution and the azimuth resolution;

[0029] Step c: Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the distance resolution and azimuth resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient.

[0030] Furthermore, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0031] Step a': determining whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the conditions, and obtaining a plurality of grid points that meet the azimuth resolution;

[0032] Step b': determining whether the range resolution of the plurality of grid points satisfying the azimuth resolution is within a range of the range resolution threshold; if so, determining whether the grid points corresponding to the range resolution satisfy the conditions, and obtaining a plurality of grid points satisfying both the azimuth resolution and the range resolution;

[0033] Step c': Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the azimuth resolution and the range resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

[0034] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0035] The method for selecting a synthetic aperture radar detection area provided by the present invention can pre-calculate the range resolution, azimuth resolution, and ground reflection coefficient of each grid point within a desired detection area before actual synthetic aperture radar image detection, thereby obtaining a two-dimensional analysis diagram that can reflect the detection capability of the synthetic aperture radar and a parameter table of the range resolution, azimuth resolution, ground reflection coefficient, coordinates, flight parameters of the carrier, and off-axis angle corresponding to the grid points that meet the conditions, thereby better guiding the synthetic aperture radar in selecting the detection area.

[0036] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0038] Figure 1 A schematic diagram of the connection between the memory and the housing in the method for selecting a synthetic aperture radar detection area provided in the first embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the connection between the first arc-shaped rod and the connecting rod in the method for selecting the synthetic aperture radar detection area provided in Example 1 of the present invention.

[0040] Reference numerals:

[0041] 1-housing; 2-memory; 3-first arc-shaped rod; 4-second arc-shaped rod; 5-connecting tube; 6-outer ring; 7-first inner ring; 8-second inner ring; 9-baffle. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0043] Example 1

[0044] This embodiment provides a method for selecting a synthetic aperture radar detection area, which includes the following steps:

[0045] The synthetic aperture radar is turned on, and the radar controller of the synthetic aperture radar sends a detection area prediction instruction;

[0046] According to the prediction instructions of the detection area, the ground reflection coefficient matrix, the distance resolution matrix and the azimuth resolution matrix of the grid points at different distance resolutions are calculated respectively;

[0047] According to the threshold range of the range resolution, the threshold range of the azimuth resolution and the threshold range of the ground reflection coefficient, the range resolution in the range resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix and the ground reflection coefficient in the ground reflection coefficient matrix are screened respectively, and a plurality of grid points meeting the conditions of the range resolution, azimuth resolution and ground reflection coefficient are obtained and graphically displayed to obtain a two-dimensional analysis diagram, and a parameter table of the range resolution, azimuth resolution, ground reflection coefficient, coordinates, flight parameters of the carrier, off-axis angle and antenna installation angle corresponding to the plurality of grid points meeting the conditions is generated;

[0048] The radar controller of the synthetic aperture radar receives the parameter table and performs image detection of the detection area that meets the range resolution, azimuth resolution and ground reflection coefficient according to the parameters in the parameter table.

[0049] According to the two-dimensional analysis diagram obtained by the above method, the beam coverage range can be divided into multiple areas to obtain the resolution distribution characteristics within the ground beam coverage range at different oblique angles, for example, resolving 1 meter × 1 meter × sigma (ground reflection coefficient) = -12, 3 meters × 3 meters × sigma (ground reflection coefficient) = -12 and 5 meters × 5 meters × sigma (ground reflection coefficient) = -12. In practical applications, for example, the grid points of the circular marks are grid points that meet the distance resolution and azimuth resolution of 1 meter × 1 meter × sigma (ground reflection coefficient) = -12, the grid points of the cross-shaped marks are grid points that meet the distance resolution and azimuth resolution of 3 meters × 3 meters × sigma (ground reflection coefficient) = -12, and the grid points of the triangular marks are grid points that meet the distance resolution and azimuth resolution of 5 meters × 5 meters × sigma (ground reflection coefficient) = -12. When the carrier needs to perform image detection with a distance resolution and azimuth resolution of 1 meter × 1 meter × sigma (ground reflection coefficient) = -12, the various parameters of the carrier and the radar can be controlled to be consistent with the various parameters corresponding to the grid points of the circular marks, so that image detection with a distance resolution and azimuth resolution of 1 meter × 1 meter × sigma (ground reflection coefficient) = -12 can be achieved, thereby guiding radar image detection.

[0050] Compared with the existing technology, the method for selecting a synthetic aperture radar detection area provided in this embodiment can precalculate the range resolution, azimuth resolution, and ground reflection coefficient of each grid point in the required detection area before the actual synthetic aperture radar image detection. This method can obtain a two-dimensional analysis diagram that can reflect the detection capability of the synthetic aperture radar and a parameter table of the range resolution, azimuth resolution, ground reflection coefficient, coordinates, vehicle flight parameters, and off-axis angle corresponding to the grid points that meet the conditions, thereby better guiding the synthetic aperture radar in selecting the detection area.

[0051] In addition, in response to the needs of radar detection capability analysis, indicators such as distance resolution, azimuth resolution and ground reflection coefficient that were previously calculated separately are comprehensively calculated and screened. The radar capability boundary is presented in multiple dimensions through two-dimensional images, and the carrier's position, three-dimensional speed and three-dimensional posture are mapped to multiple dimensions such as the radar's effective range, oblique angle and off-axis angle. The distribution characteristics of the resolution within the ground beam coverage range are given, which can more intuitively demonstrate the radar detection capability and facilitate operators to intuitively understand the radar's detection capability.

[0052] Specifically, the method for selecting the synthetic aperture radar detection area includes the following steps:

[0053] Step 1: Turn on the synthetic aperture radar, and the synthetic aperture radar controller sends a detection area prediction instruction;

[0054] According to the detection area prediction instruction, the ground beam coverage range is determined using the flight parameters of the vehicle and the antenna installation angle and scanning range of the radar. A grid is drawn within the beam coverage range to obtain the coordinate matrix of the grid points within the beam coverage range.

[0055] Step 2: Calculate the slant angle matrix and slant range matrix corresponding to the grid points within the beam coverage range based on the flight parameters of the carrier and the grid point coordinate matrix;

[0056] Step 3: Calculate the actual transmit gain matrix from the antenna to the grid point and the actual receive gain matrix from the antenna to the grid point based on the off-axis angle. It should be noted that the off-axis angle refers to the angle between the carrier target pointing and the antenna pointing;

[0057] Step 4: Calculate the radar equation based on the actual transmit gain matrix from the antenna to the grid point, the actual receive gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the radar's system loss (it should be noted that the radar's system loss is a fixed value. Each radar model has a fixed system loss, usually including waveform loss or transmission loss), and the average power to obtain the ground reflection coefficient matrix of the grid point at different range resolutions.

[0058] According to the radar bandwidth, the height of the carrier and the slant range matrix, the range resolution matrix of the grid points is obtained;

[0059] The azimuth resolution matrix of the grid points is obtained according to the carrier's velocity (which can be obtained by calculating the carrier's three-dimensional velocity), wavelength, synthetic aperture time, slant angle matrix and slant range matrix;

[0060] The range resolution in the range resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix are screened according to the threshold range, and multiple grid points that meet the conditions of range resolution, azimuth resolution, and ground reflection coefficient are obtained and graphically displayed to obtain a two-dimensional analysis diagram, and a parameter table of range resolution, azimuth resolution, ground reflection coefficient, coordinates, flight parameters of the carrier, off-axis angle, and antenna installation angle corresponding to the multiple grid points that meet the conditions is generated;

[0061] Step 5: The controller of the synthetic aperture radar receives the parameter table and performs image detection of the detection area that meets the range resolution, azimuth resolution and ground reflection coefficient according to the parameters in the parameter table.

[0062] Illustratively, in the above steps 1 and 2, the flight parameters of the carrier include the coordinates, pitch attitude, yaw attitude, roll attitude and three-dimensional velocity of the carrier in the navigation coordinate system.

[0063] It should be noted that the carrier refers to a substrate used to carry the radar, for example, an aircraft, satellite, spacecraft or other aircraft.

[0064] In step 1 above, the following method is used to obtain the grid point coordinate matrix within the beam coverage range:

[0065] T x =[x1,x2,…,x M ]

[0066] T z =[z1,z2,…,z N ]

[0067] Among them, x1, x M 、z1、z N are the coordinates of the intersection of the maximum coverage range of the beam and the two-dimensional coordinate axis of the ground, T x 、T z is the two-dimensional coordinate matrix of the grid points, x is an integer from 1 to M, and z is an integer from 1 to N.

[0068] In step 2 above, the slant angle matrix θ and slant range matrix R corresponding to the grid points within the beam coverage range are calculated based on the flight parameters of the carrier and the grid point coordinate matrix using the following formula:

[0069] θ v =arctan(v z / v x )

[0070] θ p =arctan(T z -P z ) / (T x -P z )

[0071] θ=θ p -θ v

[0072]

[0073] Among them, θ is the slant angle matrix, R is the slant distance matrix, and v x is the north velocity of the carrier in the navigation coordinate system, v z is the east speed of the carrier in the navigation coordinate system, (P x ,P y ,P z ) is the coordinate of the carrier in the navigation coordinate system, T x 、T z is the two-dimensional coordinate matrix of the grid points, x is an integer from 1 to M, and z is an integer from 1 to N.

[0074] In the above step 3, according to the off-axis angle matrix Calculate the actual transmission gain matrix G from the antenna to the grid pointtT And the actual receiving gain matrix G from the antenna to the grid point rT Use the following formula:

[0075]

[0076]

[0077] Among them, G t is the antenna transmission gain, G r G is the antenna receiving gain. Each model of GAR has a fixed G t and G r , both are known values, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, is the off-axis angle matrix.

[0078] In step 4 above, the radar equation is calculated based on the actual transmission gain matrix from the antenna to the grid point, the actual receiving gain matrix from the antenna to the grid point, the slant angle matrix, the slant range matrix, the radar's system loss, and the average power. The ground reflection coefficient matrix of the grid point at different resolutions is obtained using the following formula:

[0079]

[0080] Where σ is the ground reflection coefficient matrix, R is the slant range matrix, K = 1.38 × 10 -23 is the Boltzmann constant, T0 is the noise temperature, F n is the noise coefficient, L is the system loss, v is the sum velocity of the carrier in the north-east plane in the navigation coordinate system, θ is the oblique viewing angle matrix, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution (in this formula, is the specified value), and k=1.4 is the azimuth broadening factor.

[0081] In the above step 4, according to the radar bandwidth B r , the height of the carrier, the slant distance R matrix to calculate the distance resolution matrix D r Use the following formula:

[0082]

[0083]

[0084] Among them, D ris the distance resolution matrix, R is the slant range matrix, B r is the bandwidth of the radar, (P x ,P y ,P z ) is the coordinate of the carrier in the navigation coordinate system, k is the azimuth broadening factor, c is the speed of light, and β is the ground-grabbing angle.

[0085] The azimuth resolution matrix D is calculated based on the carrier's velocity, wavelength, synthetic aperture time, slant angle matrix and slant range matrix. a Use the following formula:

[0086]

[0087] Among them, D a is the azimuth resolution matrix, k is the azimuth broadening factor, λ is the wavelength, R is the slant range matrix, v is the sum velocity of the carrier in the northeast plane in the navigation coordinate system, θ is the slant angle matrix, T a is the synthetic aperture time.

[0088] Exemplarily, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0089] Step a: Determine whether the range resolution in the range resolution matrix is ​​within the range resolution threshold range. If so, determine whether the grid point corresponding to the range resolution meets the conditions, and obtain multiple grid points that meet the range resolution.

[0090] Step b: determining whether the azimuth resolution of the plurality of grid points satisfying the range resolution is within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the condition, and obtaining a plurality of grid points satisfying both the range resolution and the azimuth resolution;

[0091] Step c: Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the distance resolution and azimuth resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient.

[0092] Alternatively, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0093] Step a': determining whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the conditions, and obtaining a plurality of grid points that meet the azimuth resolution;

[0094] Step b': determining whether the range resolution of the plurality of grid points satisfying the azimuth resolution is within a range of the range resolution threshold; if so, determining whether the grid points corresponding to the range resolution satisfy the conditions, and obtaining a plurality of grid points satisfying both the azimuth resolution and the range resolution;

[0095] Step c': Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the azimuth resolution and the range resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

[0096] Alternatively, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0097] Step a'': determining whether a ground reflection coefficient in a ground reflection coefficient matrix is ​​within a ground reflection coefficient threshold range; if so, determining whether a grid point corresponding to the ground reflection coefficient satisfies a condition, and obtaining a plurality of grid points satisfying the ground reflection coefficient;

[0098] Step b'': determining whether the azimuth resolution of the plurality of grid points satisfying the ground reflection coefficient is within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the condition, and obtaining a plurality of grid points satisfying both the ground reflection coefficient and the azimuth resolution;

[0099] Step c”: Determine whether the range resolution of the multiple grid points that simultaneously meet the ground reflection coefficient and azimuth resolution is within the range resolution threshold. If so, determine whether the grid points corresponding to the range resolution meet the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

[0100] Alternatively, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0101] Step A: Determine whether the ground reflection coefficient in the ground reflection coefficient matrix is ​​within the ground reflection coefficient threshold range. If so, determine whether the grid point corresponding to the ground reflection coefficient meets the conditions, and obtain multiple grid points that meet the ground reflection coefficient.

[0102] Step B: Determine whether the range resolution of the multiple grid points that meet the ground reflection coefficient is within the range of the range resolution threshold. If so, determine whether the grid points corresponding to the range resolution meet the conditions, and obtain multiple grid points that simultaneously meet the ground reflection coefficient and the range resolution.

[0103] Step C: Determine whether the azimuth resolution of multiple grid points that simultaneously meet the ground reflection coefficient and distance resolution is within the azimuth resolution threshold range. If so, determine whether the grid point corresponding to the azimuth resolution meets the conditions, and obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient.

[0104] Alternatively, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0105] Step A': determining whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the conditions, and obtaining a plurality of grid points that meet the azimuth resolution;

[0106] Step B': determining whether the range resolution of the multiple grid points that meet the azimuth resolution is within the ground reflection coefficient threshold range; if so, determining whether the grid point corresponding to the ground reflection coefficient meets the condition, and obtaining multiple grid points that simultaneously meet the azimuth resolution and the ground reflection coefficient;

[0107] Step C': Determine whether the range resolution of multiple grid points that simultaneously meet the requirements of azimuth resolution and ground reflection coefficient is within the range resolution threshold. If so, determine whether the grid points corresponding to the range resolution meet the requirements, and obtain multiple grid points that simultaneously meet the requirements of range resolution, azimuth resolution, and ground reflection coefficient.

[0108] Alternatively, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0109] Step A”: determining whether the range resolution in the range resolution matrix is ​​within a range resolution threshold range; if so, determining whether the grid point corresponding to the range resolution satisfies a condition, and obtaining a plurality of grid points that satisfy the range resolution;

[0110] Step B': determining whether the azimuth resolution of the plurality of grid points that meet the range resolution is within a ground reflection coefficient threshold range; if so, determining whether the grid point corresponding to the ground reflection coefficient meets the condition, and obtaining a plurality of grid points that simultaneously meet the range resolution and the ground reflection coefficient;

[0111] Step C”: Determine whether the azimuth resolution of multiple grid points that simultaneously meet the range resolution and the ground reflection coefficient is within the azimuth resolution threshold range. If so, determine whether the grid point corresponding to the azimuth resolution meets the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

[0112] Alternatively, screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps:

[0113] At the same time, it is determined whether the distance resolution in the distance resolution matrix is ​​within the distance resolution threshold range, whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range, and whether the ground reflection coefficient in the ground reflection coefficient matrix is ​​within the ground reflection coefficient threshold range;

[0114] If the range resolution, azimuth resolution, and ground reflection coefficient are all within their respective threshold ranges, the grid points corresponding to the range resolution, azimuth resolution, and ground reflection coefficient are judged to meet the conditions, and multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient are obtained.

[0115] It is worth noting that in actual applications, the speed error and altitude error of the carrier will also affect the detection capability of the radar. Therefore, the above step 4 also includes the following steps:

[0116] Calculate the distortion rate based on the velocity error and height error of the carrier;

[0117] According to the threshold range, multiple grid points that simultaneously meet the range resolution, azimuth resolution and ground reflection coefficient are subjected to distortion screening, and the grid points after distortion screening are graphically displayed as grid points that meet the conditions.

[0118] Specifically, the calculation of the distortion rate based on the velocity error and height error of the carrier includes the following steps:

[0119] The theoretical two-dimensional positions of the four edge points of the ground beam coverage range are obtained according to the ground beam coverage range;

[0120] The carrier's 3D velocity error and height error are added to the ground beam coverage to obtain the actual ground beam coverage and the actual 2D positions of the four edge points of the actual beam coverage.

[0121] The difference between the actual two-dimensional position and the theoretical two-dimensional position is calculated, and the maximum value of the ratio of the difference to the two-dimensional width of the actual beam coverage range is the distortion rate.

[0122] Illustratively, the above-mentioned method for selecting a synthetic aperture radar detection area can adopt a synthetic aperture radar detection area selection system, which includes a radar controller, a data calculation unit, a threshold comparison unit, a graphical display unit and a data table generation unit; the instruction output end of the radar controller is connected to the data input end of the threshold comparison unit through the data calculation unit, the data output end of the threshold comparison unit is respectively connected to the graphical display unit and the data table generation unit, and the data output end of the data table generation unit is connected to the data input end of the radar controller.

[0123] The data calculation unit is used to calculate the ground reflection coefficient matrix, distance resolution matrix and azimuth resolution matrix of the grid points at different distance resolutions;

[0124] The threshold comparison unit receives the distance resolution matrix, the azimuth resolution matrix, and the ground reflection coefficient matrix respectively, and compares them with the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient stored in the threshold comparison unit, obtains a plurality of grid points that simultaneously meet the distance resolution, the azimuth resolution, and the ground reflection coefficient, and sends them to the graphic display unit and the data table generation unit respectively;

[0125] The graphic display unit graphically displays multiple grid points that simultaneously meet the range resolution, azimuth resolution and ground reflection coefficient;

[0126] The data table generation unit generates a parameter table of distance resolution, azimuth resolution, ground reflection coefficient, coordinates, flight parameters of the carrier, off-axis angle and antenna installation angle corresponding to multiple grid points that meet the conditions and sends it to the radar controller.

[0127] Specifically, in the above data calculation unit, the grid point coordinate matrix uses the following formula:

[0128] T x =[x1,x2,…,x M ]

[0129] T z =[z1,z2,…,zN ]

[0130] Among them, x1, x M 、z1、z N are the coordinates of the intersection of the maximum coverage range of the beam and the two-dimensional coordinate axis of the ground, T x 、T z is the two-dimensional coordinate matrix of the grid points.

[0131] In the above data calculation unit, the slant angle matrix θ and the slant distance matrix R are calculated using the following formula:

[0132] θ v =arctan(v z / v x )

[0133] θ p =arctan(T z -P z ) / (T x -P z )

[0134] θ=θ p -θ v

[0135]

[0136] Among them, θ is the slant angle matrix, R is the slant distance matrix, and v x is the north velocity of the carrier in the navigation coordinate system, v z is the east speed of the carrier in the navigation coordinate system, (P x ,P y ,P z ) is the coordinate of the carrier in the navigation coordinate system, T x 、T z is the two-dimensional coordinate matrix of the grid points.

[0137] In the above data calculation unit, the actual transmission gain matrix G from the antenna to the grid point is tT And the actual receiving gain matrix G from the antenna to the grid point rT The calculation is based on the following formula:

[0138]

[0139]

[0140] Among them, G t is the antenna transmission gain, G r G is the antenna receiving gain. Each model of GAR has a fixed G t and G r , both are known values, GtT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, is the off-axis angle matrix.

[0141] In the above data calculation unit, the ground reflection coefficient matrix is ​​calculated using the following formula:

[0142]

[0143] Where σ is the ground reflection coefficient matrix, R is the slant range matrix, K = 1.38 × 10 -23 is the Boltzmann constant, T0 is the noise temperature, F n is the noise coefficient, L is the system loss, v is the sum velocity of the carrier in the north-east plane in the navigation coordinate system, θ is the oblique viewing angle matrix, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution (in this formula, is the specified value), and k=1.4 is the azimuth broadening factor.

[0144] In the above data calculation unit, the distance resolution matrix D r The calculation is based on the following formula:

[0145]

[0146]

[0147] Among them, D r is the distance resolution matrix, R is the slant range matrix, B r is the bandwidth of the radar, (P x ,P y ,P z ) is the coordinate of the carrier in the navigation coordinate system, k is the azimuth broadening factor, c is the speed of light, and β is the ground-grabbing angle.

[0148] In the above data calculation unit, the azimuth resolution matrix D a The calculation is based on the following formula:

[0149]

[0150] Among them, D a is the azimuth resolution matrix, k is the azimuth broadening factor, λ is the wavelength, R is the slant range matrix, v is the sum velocity of the carrier in the northeast plane in the navigation coordinate system, θ is the slant angle matrix, T a is the synthetic aperture time.

[0151] It is worth noting that in practical applications, the speed error and height error of the carrier will also affect the detection capability of the radar. Therefore, the above-mentioned synthetic aperture radar detection area selection system also includes a distortion rate acquisition unit;

[0152] The threshold comparison unit receives the distortion rate and compares the distortion rates corresponding to multiple grid points that simultaneously meet the distance resolution, azimuth resolution and ground reflection coefficient with the threshold stored in the threshold comparison unit, obtains multiple grid points that simultaneously meet the distance resolution, azimuth resolution, ground reflection coefficient and distortion rate and sends them to the graphical display unit to display a two-dimensional analysis graph.

[0153] It can be understood that in order to realize the storage of the above-mentioned units, the above-mentioned synthetic aperture radar detection area selection system also includes a memory 2 for storing a data calculation unit, a threshold comparison unit and a graphical display unit. Exemplarily, the memory 2 can be a chip.

[0154] In order to effectively protect the memory 2, the above-mentioned synthetic aperture radar detection area selection system also includes a shell 1, and the memory 2 is arranged in the shell 1. The shell 1 can effectively protect the memory 2 and extend its service life.

[0155] In practical applications, considering that the memory 2 is an electronic device, when the carrier is an aircraft, the memory 2 will inevitably be subjected to a certain impact when the carrier lands. The above-mentioned synthetic aperture radar detection area selection system also includes a buffer, and the memory 2 is detachably connected to the housing 1 through the buffer. Figure 1 .

[0156] By way of example, the buffer member comprises a first curved rod 3, a connecting tube 5, and a second curved rod 4. One end of the first curved rod 3 is slidably connected to one end of the second curved rod 4 via the connecting tube 5. The other ends of the first curved rod 3 and the second curved rod 4 are connected to the housing 1, and the reservoir 2 is disposed on the connecting tube 5. Thus, on the one hand, because both the first curved rod 3 and the second curved rod 4 are curved, when the reservoir 2 is impacted, the first curved rod 3 and the second curved rod 4 can undergo a certain degree of elastic deformation, thereby providing a buffering effect. On the other hand, one end of the first curved rod 3 is slidably connected to one end of the second curved rod 4 via the connecting tube 5. During the elastic deformation of the first curved rod 3 and the second curved rod 4, the ends of the two rods approach each other, increasing their elastic deformation and thus further buffering the impact.

[0157] Considering that any material has a deformation limit, in order to avoid the first curved rod 3 and the second curved rod 4 from being damaged due to excessive deformation, it is necessary to appropriately limit the relative sliding displacement between the first curved rod 3 and the second curved rod 4. One end of the connecting tube 5 is sleeved on the outer wall of the first curved rod 3, and the other end of the connecting tube 5 is sleeved on the outer wall of the second curved tube. Limiting members are provided between the connecting tube 5 and the first curved rod 3 and between the connecting tube 5 and the second curved rod 4. Figure 2 .

[0158] Exemplarily, the limiting member includes an outer ring 6 provided on the outer walls of the first arc rod 3 and the second arc rod 4 and an inner ring provided on the inner wall of the connecting tube 5. The outer ring 6 is a rigid ring and the inner ring is an elastic ring. The inner diameter of the inner ring is smaller than the outer diameter of the outer ring 6. As the inner diameters of the multiple inner rings gradually decrease as they approach the midpoint of the connecting tube 5.

[0159] Taking the inner ring and outer ring 6 between the connecting tube 5 and the first arc rod 3 as an example, the number of outer ring 6 is 1, and the number of inner rings is 2, namely the first inner ring 7 and the second inner ring 8. A baffle 9 is provided on the side of the second inner ring 8 away from the first inner ring 7. When not impacted, the outer ring 6 is located on the side of the first inner ring 7 away from the second inner ring 8 and does not contact the first inner ring 7; when the elastic deformation of the first arc rod 3 is too large, the outer ring 6 squeezes the first inner ring 7 and enters between the first inner ring 7 and the second inner ring 8, and collides with the second inner ring 8, absorbing part of the impact force, and the second inner ring 8 can limit the sliding displacement between the first arc member and the connecting tube 5 to a certain extent, preventing the outer ring 6 from further sliding displacement; when the first arc rod 3 is close to the maximum elastic deformation, the outer ring 6 squeezes the second inner ring 8 and abuts against the baffle 9, thereby preventing the outer ring 6 from further sliding displacement, thereby avoiding damage to the outer ring 6.

[0160] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for selecting a synthetic aperture radar detection area, characterized in that: The steps include: Turning on a synthetic aperture radar, wherein a radar controller of the synthetic aperture radar sends a detection area prediction instruction; According to the prediction instructions of the detection area, the ground reflection coefficient matrix, the distance resolution matrix and the azimuth resolution matrix of the grid points at different distance resolutions are calculated respectively; According to the threshold range of the range resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient, the range resolution in the range resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix are screened respectively, and a plurality of grid points meeting the conditions of the range resolution, azimuth resolution, and ground reflection coefficient are obtained and graphically displayed to obtain a two-dimensional analysis diagram, and a parameter table of the range resolution, azimuth resolution, ground reflection coefficient, coordinates, flight parameters of the carrier, off-axis angle, and antenna installation angle corresponding to the plurality of grid points meeting the conditions is generated; The radar controller of the synthetic aperture radar receives the parameter table and performs image detection of the detection area that meets the range resolution, azimuth resolution and ground reflection coefficient according to the parameters in the parameter table; The ground reflection coefficient matrix of the grid points at different resolutions uses the following formula: Where σ is the ground reflection coefficient matrix, R is the slant range matrix, K = 1.38 × 10 -23 is the Boltzmann constant, T0 is the noise temperature, F n = is the noise coefficient, L is the system loss, v is the sum velocity of the carrier in the north-east plane in the navigation coordinate system, θ is the oblique viewing angle matrix, P av is the average power, G tT is the actual transmission gain matrix from the antenna to the grid point, G rT is the actual receiving gain matrix from the antenna to the grid point, SNR is the detection signal-to-noise ratio, λ is the wavelength, D r is the range resolution, k = 1.4 is the azimuth broadening factor; Distance resolution matrix D r Use the following formula: Among them, D r is the distance resolution matrix, R is the slant range matrix, B r is the bandwidth of the radar, P y , is the y-axis coordinate of the carrier in the navigation coordinate system, k is the azimuth broadening factor, c is the speed of light, and β is the ground-grabbing angle; Azimuth resolution matrix D a Use the following formula: Among them, D a is the azimuth resolution matrix, k = is the azimuth broadening factor, λ is the wavelength, R is the slant range matrix, v is the sum velocity of the carrier in the northeast plane in the navigation coordinate system, θ is the slant angle matrix, T a is the synthetic aperture time.

2. The method for selecting a synthetic aperture radar detection area according to claim 1, wherein: The system loss includes waveform loss and transmission loss.

3. The method for selecting a synthetic aperture radar detection area according to claim 1, wherein: Screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps: Step a: Determine whether the range resolution in the range resolution matrix is ​​within the range resolution threshold range. If so, determine whether the grid point corresponding to the range resolution meets the conditions, and obtain multiple grid points that meet the range resolution. Step b: determining whether the azimuth resolution of the plurality of grid points satisfying the range resolution is within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the condition, and obtaining a plurality of grid points satisfying both the range resolution and the azimuth resolution; Step c: Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the distance resolution and azimuth resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the distance resolution, azimuth resolution, and ground reflection coefficient.

4. The method for selecting a synthetic aperture radar detection area according to claim 1, wherein: Screening the distance resolution in the distance resolution matrix of the grid points, the azimuth resolution in the azimuth resolution matrix, and the ground reflection coefficient in the ground reflection coefficient matrix according to the threshold range of the distance resolution, the threshold range of the azimuth resolution, and the threshold range of the ground reflection coefficient respectively includes the following steps: Step a': determining whether the azimuth resolution in the azimuth resolution matrix is ​​within the azimuth resolution threshold range; if so, determining whether the grid point corresponding to the azimuth resolution satisfies the conditions, and obtaining a plurality of grid points that meet the azimuth resolution; Step b': determining whether the range resolution of the plurality of grid points satisfying the azimuth resolution is within a range of the range resolution threshold; if so, determining whether the grid points corresponding to the range resolution satisfy the conditions, and obtaining a plurality of grid points satisfying both the azimuth resolution and the range resolution; Step c': Determine whether the ground reflection coefficients of multiple grid points that simultaneously meet the azimuth resolution and the range resolution are within the ground reflection coefficient threshold range. If so, determine whether the grid points corresponding to the ground reflection coefficients meet the conditions, and obtain multiple grid points that simultaneously meet the range resolution, azimuth resolution, and ground reflection coefficient.

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